I. Field of Invention
The invention generally relates to cryptosystems and more particularly to generation and replacement of keys for cryptosystems.
II. Description of the Related Art
Cryptographic signatures may be generated using public-key cryptography. In public-key cryptography systems, a user has both a private key and a public key for authenticating documents. The public key is shared while the private key is kept secret. The user signs a communication with the user's private key by sending the communication along with a digital signature to a targeted entity or party, who then verifies the communication and the digital signature with the user's public key.
In one application, a public-key cryptography system may be implemented in a portable device (hereinafter token). The private and public keys are generated for the token. The private key remains in the token and the public key is sent to one or more targeted entities. The token can then be used by the owner to establish various relationships with targeted entities to enable access to doors, bank accounts, computer networks, and so on.
However, the token (and hence the private key stored in it) might be stolen, or alternatively broken, lost or destroyed. If the token is stolen, it is important to limit the damage done by the thief while the token is in their possession. If, for whatever reason, its owner just can't use it any more, the problem is more one of major inconvenience for the owner while re-establishing the various relationships enabled by the token.
Therefore, there is a need for a more convenient, efficient and/or confidential method of replacing cryptographic keys in tokens.